Polarized outlet and plug



Nov. 3, 1959 w. w. DAVIS 2,911,614

POLARIZED OUTLET AND PLUG l Filed oct. 22, 1957 77 79 3o `E J 56" If *Qn: 9? 9 m" INVENTOK. o 3 ,6, Zygfieffl@ 76 WWMWMT'W United ,StatesParent IO j 2,911,614 lPoLRIzED OUTLETAND PLUG 'j Walter W. Davis,Campton, N.H. n Application october zz, I1951, serial isa-691,711

This invention relates to electrical connector. devices, and moreparticularly to a polarized receptacle and plug arrangement for use inconjunction with domestic' power systems of the type having a groundedconductor.

A main object of the invention is to provide a novel and improvedpolarized receptacle and plug for. use therewith, thereceptacle and plugbeing especially suitable for use ini conjunction' with conventionalelectric wiring includinga grounded conductor, the receptacle and plugbeing simple in construction, being easy to install, and providing ameans whereby appliances of the polarized type may be properly connectedto the line conductors for energizing same.

A further object of the invention is to provide an improved polarizedplug and receptacle for use therewith;

the plug and receptacle being inexpensive to manufacture, beingl durablein construction, being arranged so that correct polarity is positivelymaintained, the receptacle being neat in appearance, and the plug andreceptacle being easily connected together.

A still further object ofthe invention is to provide an improved plugreceptacle of the polarized type.es.

pecially suitable for use in conjunction with domestic wiring systems,the receptacle being compact in size, b'eing arranged to firmly hold aplug inserted therein, and being provided with spacing between thecontacts thereof of suicient magnitude to insure that no short circuitswill occur in the receptacle.

Further objects and advantages of the invention will become .apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

Figure l is a vertical cross sectional view taken through an improvedpolarized receptacle according tothe present invention, shown withfapolarized plug engaged therein.

Figure 2 is anV enlarged longitudinal vertical cross sectional viewtaken through the plug employed in Figure 1.

Figure 3 is a transverse vertical cross sectional view taken on the line3-3 of Figure 2.

Figure 4 is a top VView of the main body portion of the plug of Figures2V and 3, the outer cover thereof being removed.

Figure 5 is a transverse vertical cross sectional view taken on the line5-5 of Figure 2. i

Figure 6 is a horizontal cross sectional view taken on the line 6-6 ofFigure 1.

Figure 7 is a horizontal cross sectional view taken on the line 7-7 ofFigure l.

Figure 8 is a cross vsectional view taken on the line 8 8 of Figure 6.

Figure 9 isv a cross sectional view taken on the line 9-9 of Figure 6. vY i Figure l0 is a fragmentary horizontal cross sectional View taken onthe line 10`10 of Figure 2.

, Figure l1 is a fragmentary vertical cross sectional viewA takenthrough the upperportion of a modified form of polarized plugreceptacleaccording to the` pres# Patented Nov. 3, 1959 ICC 2 entinvention adapted for a three-wire circuit and shown with athree-contact plug engaged in the receptacle.

Figure 12 is a top plan view of the main body portion of thethreecontact plug employed in Figure l1.

vFigure 13 is a transverse vertical cross sectional view taken on theline 13-13 of Figure l2.

Referring to the drawings, and more particularly to Figures/1 to 10, 14designates a conventional outlet box provided with a suitab-lereceptacle-supporting strap 15 in which is secured a polarized plugreceptacle according to the present invention, and designated generallyat 16.

The receptacle 16 comprises a pair of opposed, hollow, mating, generallyrectangular housing segments 17 and 18 .of rigid insulating material,such as rigid plastic material, the-hollow segments 17 and 18 beingsecured together in opposing relationship to dene a rectangular housingby an internally threaded sleeve member 21 having head portions 22 and22 4at its opposite ends. The` sleeve member 21 extends through acentral aperture in the'bight portion of the receptacle bracket member15=fand acts as a hollow rivet to fasten members 15, 17 and 18 together.A machine screw 19 extends through the center portion of a rectangularface plate l20 and is threadedly engaged in the internally threadedsleeve member 21.

The sleeve 21 passes through a central, generally rectangular spacingblock 25 of rigid insulating material whichfits snugly in theintermediate portion of the cavity l:defined between the opposinghousing segments 17andV 18. Clamped between block Z5 and the major wallof housing segment 17 is a rear contact plate Z6, clearly shown inFigure 9, said contact plate being genrally V-shaped and being formed atits opposite ends with apertures 27, 27 adapted to receive the ball endof a connecting plug, presently to be described. The end portions of theterminal plate 26 are fonned with inwardly extending spring contactngers 28 which are spaced around the apertures 27, as shown in Figures land 9,Y said contact fingers 2S being adap-ted to receive the ball end30 of a plug therebetween and to exert a locking action on said ball endto retain the plug in the receptacle, as will be presently explained.

'The intermediate portion of the terminal plate 26 is formed with aterminal flange 31 exposed through a notch inthe adjacent side wall ofhousing segment 17, as shown in Figure 6, said flange 31 being providedwith terminal screws 33 which provide a means for electricallyconnecting terminal conductor 34 to the terminal plate 26.

Clamped between the block 25 and the inside surface of the major wall ofhousing segment 18 is a generally V-shaped terminal plate 35, saidterminal plate being formed at its end portions with ring-like members36, 36, defining apertures similar to the apertures 27, said ringlikemembers 36,Y 36 being formed with inwardly projecting, spaced springcontact fingers 37 adapted to conductively and grippingly engage withthe conductive sleeve portion 56 of a plug 39 when the contact plug isinserted in the receptacle in the manner illustrated in Figure 1. Theterminal platemember 35 is provided at its intermediate portion with aterminal Flange 40 rwhich is exposed through a notch in the side wall ofhousing segment 18, as shown in Figure 6, said ange 40 being providedwith terminal screws 42. The terminal screws 42 are vadapted -to beconnected to the grounded conductor 44 of a house wiring system.

As shown in Figures 8 and 9, the fastening sleeve 21 extends vthroughthe aligned contact plates 26 and 35, being;I located substantiallymidway between and in the same' plane as the axes of the ring-likemembers at thek ends'of said plates. i

As shown inFigure 1, the housing segment 18 is formed with conical,inwardly convergent apertures 45' 3 aligned with the spaced aperturedend portions of the respective terminal plates 26 and 35.

The plug 39, above mentioned, comprises a main body 46, of suitableinsulating material, said main body having integrally moulded thereinthe shank member' 47 whose outer end is formed with the ball contactelement 30. A terminal screw 48 is engaged through the inner end of theshank 47 and is adapted to electrically conlnect a conductor 49 to saidshank member 47, the conductor 49 forming part of `an appliance cord 50,as shown in Figure 2.

The body 45 is formed with a reduced for-ward portion 51 and with aconical shoulder 54 adapted to it the conical apertures 45 in the frontwall of housing section 18. A grooove 52 is formed between the forwardend of the reduced portion 51 and the conical shoulder 54, andpositioned in this groove is a contact sleeve member 56 having a stemportion 57 moulded in the body 54 andv extending a substantial distanceinwardly thereof. A terminal screw 58 extends through the inner end ofthe stem 57 and is threadedly engaged in the body 46, the shank 47 beingbowed at its intermediate portion, as shown at 59 in Figure 10, toprovide clearance between said shank portion and the terminal screw 58.The remaining conductor 60 of the line cord 50 is adapted to beconnected to the terminal screw 58, and hence to the contact sleeve 56.As shown in Figure 4, the contact sleeve 56 is substantially ilush withthe forward portion 51 of main body 46, and is coaxially arranged withre-v spect to the shank 47.

Designated at 62 is a cover member which is securedy over the rearportion of the plug body 46, as by means of a fastening screw 63 whichextends through and is suitably insulated from the rear end portion ofshank 47 and which is threadedly engaged inthe rear portion vofy body46. The cover member 62 houses the terminal screws 4S and 58 and ispreferably made ofinsulating material. Line cord 50 extends through anaperture 65 formed in the rear end wall of the generally cylindricalcover 62. v

As shown in Figure l, the plug 39 is easily inserted in the receptacle16 through one of the conical apertures 45, the ball-shaped end 30 ofthe shank 47 being grippingly received betweenthe spring-like contactfingers `28 and being locked thereby, whereas the sleeve element 56 isconductively engaged by the resilient fingers 37 ofthe grounded terminalplate 35. Thus, positive assurance is4 provided that the line conductor60 ofvcord 50 will always be connected to the grounded conductor of thewiring system, so that the appliance, if it -be of the polarized typewherein one conductor must be connected to the ground wire of theelectric supply system, will lways be connected to the supply circuit'with the proper polarity.

In the form of the invention shown in Figures 1.1, "12' and 13, thereceptacle, designated generally at 1'6 is provided with a thirdterminal plate 70 spaced between the inner terminal plate 26 and theouter terminal plate 35 by respective insulating spacer blocks 71 and7'2'*V through which the main fastening sleeve 21 passes.Y Theintermediate terminal plate 70 is provided with apertures, around whichare resilient contact lingers 74 adapted to;

gaged in the inner end of the shank element of the plug, designated at83. The respective Wires of a conventional three-wire line cord may beclampingly secured by the terminal screws 79, 81 and 82, and may be thuselectrically connected respectively to sleeve member 75, sleeve member56', and shank member 83 in the manner illustrated in Figure 12.

A generally cylindrical coverrg receives the rear end portion of theplug body 78 and is detachably secured thereto by a fastening screw 63in the same manner as previously described in connection with thetwo-wire plug 39. A A

Thepolarized outlets and plugs above described are especially usefulpower tools and other electrical appliances requiring a special orsecond ground wire to provide safety against shock.

By the use of the present invention, the second ground or safety wire iseliminated, since the safety wire may be connected to the body of thetool or appliance itself, and thepolan'zed plug insures proper groundingof said body. rlfhis safety feature may be employed with all appliances.

` In wiring installations where Romex cable is used, the Outlet boxesare not grounded (unless special grounded Romex cable is used) therebymaking the safety ground wire of thepower tool or appliance useless. Byemploying polarized outlets and plugs, according to this invention, insuch installations, maximum protection against shock is provided at alltimes, using one line wire and one ground wire. v

While certain specic embodiments of an improved polarized receptacleand.' plug have been disclosed in the foregoing description, it will beunderstood that various Y- modifications within the spirit of theinvention may occur to those skilled in the art. Therefore, it isintendedthat no limitations be placed` on the'invention except asdefined by the scope of the appended claims.

What is claimed is:

l. A plug receptacle for use with a plug of the type comprising acontact shank having a contact ball at its end and a contact sleevesurrounding said shank and insulated therefrom comprising a housinghaving parallel front and rear walls and opposite side walls, a firstsubstantially V-shaped terminal plate secured to the inside surface ofsaid front wall, a second substantially V-shaped terminal plate securedto the inside surface of said rear wall opposite said first V-shapedplate and parallel thereto, said front wall being formed with aperturesto receive said plug, said terminalplates being formed with ringlikemembersl at their ends defining apertures aligned with said first-namedapertures, 'a transverse fastener extending through said front and rearwalls and between the side arms of said V-shaped terminal plates insubstantially the same'plane as the axes of said apertures, spring`conengage a terminal sleeve 75 on a threelwire plug 76, the

terminal sleeve 75 being spaced between and insulated from the ball end30of the shank of the plug and the ground sleeve 56 of the plug. l i yAs shown in Figure 13, the ground sleeve 56 is formed with a contact arm77 which is moulded in and extends longitudinally of the main body ofthe plug, shown'af; 78, the arm 77 being threadedly engagedV by a`terminal screw 79, shown in Figure l2. The contact sleeve l75' issimilarly formed with an arm 80 which is embedded.

in and extends longitudinally of the body 78, a terminalv f screw 81being threadedlyengaged in the inner`l end of the afm` 89- A thirdtamirlslrserew Slis thtssdely sa' tact fingers on the first terminalplate extending inwardly and rearwardly from the apertures therein andbeing engageable with the contact sleeve of the plug, and springlcontact lingers on the second terminal plate extending inwardlyand-'forwardly from theapertures therein and being engageable with thecontact ball of the plug.

Z. A plug receptacle for use with a plug of the type comprising acontact shank having a contact ball at its end-and a Contact sleevesurrounding said shank and insulated therefrom comprising a housinghaving parallel front andrear walls and opposite side walls, a rstsubstantially V-shaped terminal plate secured to the inside surfaceofsaid front wall, asecond substantially V-haped terminal plate securedto the inside surface of said rear wall oppositetsaid first V-shapedplate .and parallel thereto, said front wall being formed withaperturestto receive said plug, said terminal plates being formed withringlike members at theirends defining, apertures aligned withsaidrst-named apertures, a transverse fastener extending through saidfront and rear walls and between the Side arms OfSaiSlV-Shsrsterminelplats ,iasubstsntally the same plane as the axes ofsaid apertures, spring contact ngers on the terminal plate spaced aroundthe apertures therein and extending inwardly and rearwardly, saidcontact ngers being engageable with the contact sleeve of the plug, andspring contact ngers on the second terminal plate extending inwardly andforwardly from the apertures therein, said last-named contact ngersbeing spaced around the apertures in the second terminal plate and beingformed and arranged to receive and lockingly engage with the contactball of the plug.

3. A plug receptacle for use with a plug of the type comprising acontact shank having a contact ball at its end and a contact sleevesurrounding said shank and insulated therefrom comprising a housinghaving parallel front and rear walls and opposite side walls, a trstsubstantially V-shaped terminal plate secured to the inside surface ofsaid front wall, a second substantially V-shaped terminal plate securedto the inside surface of said rear wall opposite said rst V-shaped plateand parallel thereto, said front wall being formed with apertures toreceive said plug, said terminal plates being formed with ringlikemembers at their ends defining apertures aligned with said first-namedapertures, a transverse fastener extending through said front and rearwalls and between the side arms of said V-shaped terminal plate insubstantially the same plane as the axes of said apertures, springcontact fingers on the iirst terminal plate spaced around the aperturestherein and extending inwardiy and rearwardly, said Contact lingersbeing engageable with the contact sleeve of the plug, springcontact'ngers on the second terminal plate extending inwardly Aandforwardly from the apertures therein, said last-named Contact ngersbeing spaced around the apertures in the second terminal plate and beingformed and arranged to receive and lock- References Cited in the le ofthis patent UNITED STATES PATENTS 2,221,280 Woodside Nov. 12, 19402,228,683 Barrelle Jan. 14, 1941 Walton et al May 10, 1949

